INC: Difference between revisions

Latest revision as of 02:07, 10 December 2023


Basic Info
Addressing Mode	Opcode	Length	Speed
Accumulator	1A	1 byte	2 cycles
Absolute	EE	3 bytes	6 cycles*
Direct Page	E6	2 bytes	5 cycles*
absolute indexed X	FE	3 bytes	7 cycles*
direct page indexed X	F6	2 bytes	6 cycles*


Flags Affected
N	V	M	X	D	I	Z	C
	.	.	.	.	.		.

INC (Increment) is a 65x instruction that increments the value in the location specified by the operand. The size of the accumulator determines whether this is an 8 or 16 bit operation.

INC ignores the decimal mode flag.

Cycle Penalties

Except in accumulator addressing, INC takes two extra cycles when the accumulator is 16 bits wide.
In direct page addressing modes, INC takes an extra cycle if the low byte of the direct page register is nonzero.

External Links

Eyes & Lichty page 456, on INC: https://archive.org/details/0893037893ProgrammingThe65816/page/n482
Labiak page 142 on INC: https://archive.org/details/Programming_the_65816/page/n152
MCS6500 Manual page 155 on INC: https://archive.org/details/mos_microcomputers_programming_manual/page/n176
Carr page 260 on INC: https://archive.org/details/6502UsersManual/page/n273
Leventhal page 3-65 on INC: https://archive.org/details/6502-assembly-language-programming/page/n114
snes9x implementation of INC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L627
undisbeliever on INC: https://undisbeliever.net/snesdev/65816-opcodes.html#inc-increment

@@ Line 1: / Line 1: @@
-'''INC''' (Increment) is a 65x instruction that increments the value in the location specified by the operand.
+{| class="wikitable" style="float:right;clear:right;width:40%"
+!colspan="8"|Basic Info
+|+
+|'''Addressing Mode'''
+|'''Opcode'''
+|'''Length'''
+|'''Speed'''
+|+
+|[[Accumulator Addressing | Accumulator]]
+|1A
+|1 byte
+|2 cycles
+|+
+|[[Absolute Addressing | Absolute]]
+|EE
+|3 bytes
+|6 cycles*
+|+
+|[[Direct Page Addressing | Direct Page]]
+|E6
+|2 bytes
+|5 cycles*
+|+
+|absolute indexed X
+|FE
+|3 bytes
+|7 cycles*
+|+
+|direct page indexed X
+|F6
+|2 bytes
+|6 cycles*
+|}
 {| class="wikitable" style="float:right;clear:right;width:30%"
-!colspan="9"|Flags Clobbered
+!colspan="9"|Flags Affected
 |+
-|N
+|[[N Flag|N]]
-|V
+|[[V Flag|V]]
-|M
+|[[M Flag|M]]
-|X
+|[[X Flag|X]]
-|D
+|[[D Flag|D]]
-|I
+|[[I Flag|I]]
-|Z
+|[[Z Flag|Z]]
-|C
+|[[C Flag|C]]
 |+
 |
@@ Line 22: / Line 54: @@
 |.
 |}
+'''INC''' (Increment) is a 65x instruction that increments the value in the location specified by the operand.  The size of the [[accumulator]] determines whether this is an 8 or 16 bit operation.
+INC ignores the [[decimal mode flag]].
+===== Cycle Penalties =====
+* Except in [[accumulator addressing]], INC takes two extra cycles when the accumulator is 16 bits wide.
+* In [[direct page addressing]] modes, INC takes an extra cycle if the low byte of the [[direct page register]] is nonzero.
 === See Also ===
+* [[INX]]
+* [[INY]]
 * [[DEC]]
+=== External Links ===
+* [[Eyes & Lichty]] page 456, on INC: https://archive.org/details/0893037893ProgrammingThe65816/page/n482
+* [[Labiak]] page 142 on INC: https://archive.org/details/Programming_the_65816/page/n152
+* [[MCS6500 Manual]] page 155 on INC: https://archive.org/details/mos_microcomputers_programming_manual/page/n176
+* [[Carr]] page 260 on INC: https://archive.org/details/6502UsersManual/page/n273
+* [[Leventhal]] page 3-65 on INC: https://archive.org/details/6502-assembly-language-programming/page/n114
+* snes9x implementation of INC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L627
+* undisbeliever on INC: https://undisbeliever.net/snesdev/65816-opcodes.html#inc-increment
 [[Category:ASM]]
+[[Category:Group Two Instructions]]
+[[Category:Read-Modify-Write Instructions]]
+[[Category:Inherited from 6502]]